The couple, who were planning a spring wedding, became engaged in April, when Cutler popped the question in Mexico. They had been spending much of their time recently in Chicago, and Cavallari had planned to move there during the upcoming football season.

"She was planning her dream wedding, the date was set, the location – everything was set," the source says. "She's in shock that the dream wedding she was planning is going to end this way."

Just a week ago, Cavallari Tweeted about her engagement party. "Thx to all my amazing friends for making my engagement party a blast last night!" she wrote.